The site's founder, moot, had to cut all ties with the site as it turned into an angry mob. It's no longer a fun and happy place, there's an undercurrent of hate, fear, and misogyny.
This is the same phenomenon that played out at Reddit where the leadership was hesitant to try and interfere with so-called free-speech issues, and would then wildly over-react when things came to a head.
The problem is that 4chan's tone has turned from "social justice", those incidents early in its history where people were genuinely trying to help others as internet vigilantes, to those that started antagonizing people, and later, to viciously harassing them.
A lot of people who wanted no part of that have left. This skews the community heavily towards those who don't leave, who enjoy that sort of thing.
I'm not saying all participants in 4chan are guilty, but the nature of that entity, as a whole, is the polar opposite of SJW.